clc, clear
close all

theta = 0:0.001:2*pi;
rho1 = cos(7*theta/2);
rho2 = 1 - cos(7*theta).^3;

figure(1)
subplot(121);
polar(theta, rho1,'--r');
title('\rho = cos(7\theta/2)')
subplot(122);
polar(theta, rho2,'--b');
title('\rho = 1 - cos^3(7\theta)')